In-line sandwich seams

ABSTRACT

The present invention is both a method for manufacturing a papermaker&#39;s dryer fabric and other seamed industrial fabrics, and the fabric made in accordance with the method. The industrial fabric has a main portion and first and second ends, and may be woven so as to have a first weave pattern at the main portion and a second weave pattern different from the first weave pattern at the first and second ends. The second weave pattern forms an upper layer and a lower layer with a pocket therebetween at the first and second ends. The industrial fabric further has a seaming member at least partially disposed in the pocket and attached to the respective upper layer and lower layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates primarily to the papermaking arts.Specifically, the present invention relates to seamed woven fabrics foruse on papermaking machines.

2. Description of the Prior Art

During the papermaking process, a cellulosic fibrous web is formed bydepositing a fibrous slurry, that is, an aqueous dispersion of cellulosefibers, onto a moving forming fabric in the forming section of a papermachine. A large amount of water is drained from the slurry through theforming fabric, leaving the cellulosic fibrous web on the surface of theforming fabric.

The newly formed cellulosic fibrous web proceeds from the formingsection to a press section, which includes a series of press nips. Thecellulosic fibrous web passes through the press nips supported by apress fabric, or, as is often the case, between two such press fabrics.In the press nips, the cellulosic fibrous web is subjected tocompressive forces which squeeze water therefrom, and which adhere thecellulosic fibers in the web to one another to turn the cellulosicfibrous web into a paper sheet. The water is accepted by the pressfabric or fabrics and, ideally, does not return to the paper sheet.

The paper sheet finally proceeds to a dryer section, which includes atleast one series of rotatable dryer drums or cylinders, which areinternally heated by steam. The newly formed paper sheet is directed ina serpentine path sequentially around each in the series of drums by adryer fabric, which holds the paper sheet closely against the surfacesof the drums. The heated drums reduce the water content of the papersheet to a desirable level through evaporation.

It should be appreciated that the forming, press and dryer fabrics alltake the form of endless loops on the paper machine and function in themanner of conveyors. It should further be appreciated that papermanufacture is a continuous process which proceeds at considerablespeeds. That is to say, the fibrous slurry is continuously depositedonto the forming fabric in the forming section, while a newlymanufactured paper sheet is continuously wound onto rolls after it exitsfrom the dryer section.

Contemporary fabrics are produced in a wide variety of styles designedto meet the requirements of the paper machines on which they areinstalled for the paper grades being manufactured. Generally, theycomprise a woven base fabric which, depending upon the application mayinclude needled batt of fine, non-woven fibrous material. The basefabrics may be woven from monofilament, plied monofilament,multifilament or plied multifilament yarns, and may be single-layered,multi-layered or laminated. The yarns are typically extruded from anyone of the synthetic polymeric resins, such as polyamide and polyesterresins, used for this purpose by those of ordinary skill in the papermachine clothing arts.

Woven fabrics take many different forms. For example, they may be wovenendless, or flat woven and subsequently rendered into endless form witha seam. Alternatively, they may be produced by a process commonly knownas modified endless weaving, wherein the widthwise ends of the basefabric are provided with seaming loops using the machine-direction (MD)yarns thereof. In this process, the MD yarns weave continuouslyback-and-forth between the widthwise ends of the fabric, at each endturning back and forming a seaming loop. A base fabric produced in thisfashion is placed into endless form during installation on apapermachine, and for this reason is referred to as anon-machine-seamable (OMS®) fabric. To place such a fabric into endlessform, the two widthwise ends are brought together, the seaming loops atthe two ends are interdigitated with one another, and a seaming pin orpintle is directed through the passage formed by the interdigitatedseaming loops.

In any event, woven fabrics are typically in the form of endless loops,or are seamable into such forms, having a specific length, measuredlongitudinally therearound, and a specific width, measured transverselythereacross. Because paper machine configurations vary widely, papermachine clothing manufacturers are required to produce fabrics, andother paper machine clothing, to the dimensions required to fitparticular positions in the paper machines of their customers. Needlessto say, this requirement makes it difficult to streamline themanufacturing process, as each fabric must typically be made to order.

Fabrics in modern papermaking machines may have a width of from 5 toover 33 feet, a length of from 40 to over 400 feet and weigh fromapproximately 100 to over 3,000 pounds. These fabrics wear out andrequire replacement. Replacement of fabrics often involves taking themachine out of service, removing the worn fabric, setting up to installa fabric and installing the new fabric.

In the case of dryer fabrics, in particular, such fabrics were producedby flat weaving and then joined together. Dryer fabrics that are usedtoday are long and require a seam for installation, since dryer sectionframes are solid without cantilever components and thus prevent the useof endless woven fabrics. Accordingly, the fabrics must be installedwith a seam, since they cannot be put on endless.

The seam region of any workable fabric must behave in use as close tothe body of the fabric in order to prevent the periodic marking by theseam region of the paper product being manufactured.

Seams may be sewn on which involves a woven web or spiral lace sewn ontoboth cross-machine direction (“CD”) ends of the dryer fabric. The wovenweb contains connecting loops which are meshed together to form theseam. The woven web, since it is out of plane and thicker than thefabric body, also tends to bump around fabric support rolls, marks thesheet, and has zero permeability, which further exacerbates the sheetmarking problem. The woven web are attached to the surface areas of thefabric, for example, the top side, or the top side and the bottom side.Since the webbing is sewn on the fabric, the webbing and the stitchingare exposed to the sheet resulting in sheet marking.

The market today is dominated by dryer fabrics having pin or coil “wovenin” seams. These seams may require MD yarns to be woven back into thefabric body by hand or machine assisted. Further, CD yarns must beraveled out. These seams are expensive to make, since they are laborintensive.

Obviously, there are other ways to provide seamable fabrics for use inpapermaking and other industrial applications, with the foregoing beingset forth merely as examples. However, as with anything, there is alwaysa desire to improve on or provide an alternative to what has been donepreviously. Seamable fabrics are no exception. In this regard,heretofore providing a seam on a fabric has been relatively timeconsuming and labor intensive. If these are aspects that can be improvedupon, this would obviously be a desirable result.

SUMMARY OF THE INVENTION

Accordingly, the present invention is both a method for manufacturing apapermaker's dryer fabric or other seamed industrial fabrics, and thefabric made in accordance with the method.

The present invention provides an industrial fabric for use in apapermaking machine. The industrial fabric has a main portion and firstand second ends, and may be woven so as to have a first weave pattern atthe main portion and a second weave pattern different from the firstweave pattern at the first and second ends. The second weave patternforms an upper layer and a lower layer with a pocket therebetween at thefirst and second ends. The industrial fabric further has a seamingmember at least partially disposed in the pocket and attached to therespective upper layer and lower layer.

The present invention also provides a method of forming an industrialfabric for use in a papermaking machine. The method includes the stepsof forming a main portion of the fabric with a first weave pattern,forming first and second ends with a second weave pattern different fromthe first weave pattern in which the second weave pattern forms an upperlayer and a lower layer with a pocket therebetween, disposing a seamingmember at least partially in the pocket; and attaching the seamingmember to the respective upper layer and lower layer.

The present invention will now be described in more complete detail withreference being made to the figures identified as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a seamed fabric;

FIG. 2 is a schematic perspective view of first and second ends of thefabric prior to their being joined to one another;

FIG. 3 is a schematic cross-sectional view of an end of the fabric; and

FIG. 4 is a top plan view of the seam, incorporating the teachings ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now specifically to the figures, FIG. 1 is a schematicperspective view of the seamed dryer fabric 1 for use in the dryersection of a papermaking machine. However, it should be noted that theinvention is applicable to other seamed industrial fabric applications,such as coarse pulp forming fabrics and other industrial fabrics usedfor the dewatering of recycled deinked pulp and industrial sludge. Alsoincluded but not limited to, are fabrics that are used in the productionof nonwoven structures such as by processes including melt blowing, airlaying, or spunbonding.

Fabric 1 includes main portion 10 taking the form of an endless loopafter a first end 12 and a second end 14 have been joined to one anotherat seam 16.

FIG. 2 is a schematic perspective view of main portion 10, and the firstend 12 and the second end 14 of fabric 1 prior to their attachments toone another. Widthwise across each of the first and second ends 12, 14are a plurality of seaming members 18 having insertion elements 20 andconnecting elements 22. To attach the first end 12 and second end 14 toone another, they are brought together by intermeshing, orinterdigitating, connecting elements 22 at each end with one another.The interdigitated connecting elements 22 define a passage through whicha pin, a pintle, a yarn-like strand or member, may be directed to securethe first end 12 and second end 14 to one another by way of the “pinseam” so formed.

FIG. 3 is a cross-sectional view of the first end 12 of fabric 1. Fabric1 has main portion 10 formed from a first weave pattern. The first weavepattern is such that a plurality of interwoven layers are formed, i.e.,a multi-layer weave. For example, the multi-layer weave may be atwo-layer weave having at least one warp system, and at least one weftsystem. Alternatively, the multi-layer weave may be three-layer fabricshaving at least two different warp systems, and at least two differentweft systems. Note that the terms “weft”, and “CD yarns” areinterchangeable in this context. Similarly, the terms “warp” and “MDyarns” are interchangeable. As shown, main portion 10 is a double layerfabric, however, other types of weave patterns suitable for the purposemay be used as will be known to those so skilled in the art.

The first end 12 is formed from a second weave pattern different fromthe first weave pattern. The second weave pattern is such that twoseparate layers are formed at the first end 12 and the second end 14forming a pocket 28 therebetween. That is, two separate layers may becreated as extensions of main portion 10 by changing the weave pattern.Thus, as is shown in FIG. 3, upper layer 24 and a lower layer 26 areformed from a second weave pattern having a pocket 28 therebetween.Here, each of upper layer 24 and lower layer 26 is a single layer havinginterwoven MD yarns 30 and CD yarns 32. However, upper layer 24 andlower layer 26 may be formed from other types of weaves suitable for thepurpose as will be known to those so skilled in the art, with theproviso that upper layer 24 and lower layer 26 form a pocket 28. The CDyarns in these two separate layers can also be of a smaller diameterthan the CD yarns in the main section of the fabric. Or the CD yarns inthe top layer or the bottom layer can be of a smaller diameter. This isto minimize the fabric thickness difference in between the seam area andthe main fabric body.

Fabric 1 further includes seaming member 18 at least partially disposedin pocket 28 and attached to upper layer 24 and lower layer 26. Theseaming member 18 may be formed of a single piece that is the full widthof the fabric, or formed from smaller segments each less than the fullwidth of the fabric. Seaming member 18 includes an insertion element 20and a connecting element 22. Insertion element 20 may be formed from awoven web or fabric, a nonwoven web, or the like. However, other typesof material suitable for the purpose may be used as will be known tothose so skilled in the art. Further, insertion element 20 may be madefrom a material that is different from the material making up mainportion 10 and/or upper and lower layers 24, 26.

Connecting element 22 may be a seaming loop, a spiral or the like. Notewhile loops or spirals are being referred to other types of seaming orcoupling elements suitable for the purpose may be used as will be knownto those so skilled in the art. Connecting elements 22 may be made ofany material suitable for the purpose (e.g. polyester, polyamide,polyethelyne, Ryton, PEEK, metal, etc.).

Insertion element 20 carries connecting element 22. That is, connectingelement 22 may be affixed to insertion element 20 by any means known tothose so skilled in the art, such as sewing and/or bonding.

Insertion element 20 may be partially or fully disposed in pocket 28.For example, as shown in FIG. 3, insertion element 20 may be disposedand sandwiched by upper layer 24 and lower layer 26. Insertion element20 may be used to attached or secure seaming member 18 to upper layer 24and lower layer 26, for example, by sewing, bonding or the like.However, other securing methods may be used suitable for the purpose aswill be known to those so skilled in the art.

For example, as shown in FIG. 3, insertion element 20 may be sewnin-line with thread 38 to upper layer 24 and lower layer 26. One methodof sewing a thread in-line is to remove at least one CD yarns from upperlayer 24 and lower layer 26 at predetermined locations 34, 36. Thepredetermined locations 34 in upper layer 24 may align vertically withpredetermined locations 36 in lower layer 26. The CD yarns may beremoved by hand or purposefully left out by skipping picks (not weavingin a CD yarn) during weaving of upper layer 24 and lower layer 26 byskipping picks at predetermined locations 34, 36. The spaces created bythe CD yarn removal provides sewing guides and seats for sewing thread.Furthermore, a solvent soluble yarn could be used as the “removablepick” and of course removed prior to sewing in the element 18. Solvroncould be the yarn used, and water can be the solvent. A thread 38 maythen be sewn through predetermined locations 34 and 36 to attachinsertion element 20 of seaming member 18 to upper layer 24 and lowerlayer 26.

The pattern of the stitching used to attach seaming member 18 may takeon various forms. In addition, the depth of the stitch in the fabric mayalso vary. Also, it may be desired to have a preliminary stitch togenerally affix or align the seaming member 18 on first end 12 andsecond end 14 and once aligned, implement a main stitching. The amountof stitching necessary should, however, be within the plane of thefabric thickness. The amount, depth and pattern of the stitching usedfor this purpose would be readily apparent to those of ordinary skill inthe art.

The yarn or thread 38 may be made of any material suitable for thepurpose (e.g. industrial polyester, nylon, Nomex®, Kevlar® (aramids),Spectran® (HMPE), Vectran® (LCP) and Tenara® and other polymers). Thesize of the thread 38 will depend upon the application and strengthrequirements. The yarns or thread used may be of a diameter of less thanor equal to the diameter of the MD or CD yarns at first end 12 andsecond end 14.

Second end 14 may be formed in a manner similar to first end 12 which isdescribed in FIG. 3.

FIG. 4 is a top plan view of seam 16, incorporating the teachings of thepresent invention. After seaming members 18 are attached to each of thefirst end 12 and the second end 14, the first end 12 and the second end14 are brought together and the connecting elements 22 are intermeshedor interdigitated with each other so as to define a passage. A pin orpintle 40 is then inserted into the passage securing the ends 12, 14 toeach other.

First end 12 and second end 14 are preferably even, so that when theyare joined together the fabric appears as a typical prior art dryerfabric but with a simpler to produce seam. Also, in a normal pin seam orwoven in spiral seam, the MD yarn counts and position at each fabricedge must match. This is a time consuming process step and can add costor reduce fabric yield (sellable square meters). An advantage of thesewn in seam is that the MD ends don't directly form the seam loops orare used for the connection of a seam spiral, so they do not have tomatch perfectly, although such matching is preferred.

The present invention may provide a more even caliper profile along theseam area than seams that are attached to the fabric surface. Further,the present invention may reduce manufacturing time and cost because thesandwich seam does not require the use of machine joining or weavingyarns back into the structure body.

Although a preferred embodiment has been disclosed and described indetail herein, its scope should not be limited thereby; rather its scopeshould be determined by that of the appended claims.

1. An industrial fabric for use in a papermaking machine, said fabrichaving a main portion and first and second ends and being woven so as tohave a first weave pattern at said main portion and a second weavepattern different from said first weave pattern at said first and secondends, said second weave pattern forming an upper layer and a lower layerwith a pocket therebetween at said first and second ends, said fabricfurther having a seaming member at least partially disposed in saidpocket and attached to said respective upper layer and lower layer. 2.The industrial fabric according to claim 1, wherein said seaming memberincludes an insertion element and a connecting element.
 3. Theindustrial fabric according to claim 2, wherein said insertion elementis disposed in said pocket.
 4. The industrial fabric according to claim2, wherein said insertion element is a woven web.
 5. The industrialfabric according to claim 2, wherein said connecting element is aseaming loop or a spiral.
 6. The industrial fabric according to claim 1,wherein said main portion is formed from a plurality of interwovenlayers.
 7. The industrial fabric according to claim 1, wherein each ofsaid upper and lower layers is a single layer having interwoven machinedirection (MD) yarns and cross-machine direction (CD) yarns.
 8. Theindustrial fabric according to claim 7, wherein at least one CD yarn isremoved from each of said upper and lower layers at predeterminedlocations.
 9. The industrial fabric according to claim 8, wherein saidpredetermined locations in said upper layer align vertically with saidpredetermined locations in said lower layer.
 10. The industrial fabricaccording to claim 9, wherein a thread is sewn through saidpredetermined locations to attach said seaming member to said upper andlower layers.
 11. The industrial fabric according to claim 1, whereinsaid seaming member is sewn to said upper and lower layers.
 12. Theindustrial fabric according to claim 11, wherein said seaming member issewn in-line.
 13. The industrial fabric according to claim 1, whereinsaid seaming member is a single piece having the same width of thefabric.
 14. The industrial fabric according to claim 1, wherein saidseaming member is formed from smaller segments each having less than thewidth of the fabric.
 15. The industrial fabric according to claim 1,wherein the industrial fabric is a dryer fabric for use in a dryingsection of a papermaking machine.
 16. A method of forming an industrialfabric for use in a papermaking machine, said method comprising thesteps of: forming a main portion of said fabric with a first weavepattern; forming first and second ends with a second weave patterndifferent from said first weave pattern, said second weave patternforming an upper layer and a lower layer with a pocket therebetween,disposing a seaming member in said pocket; and attaching said seamingmember to said respective upper layer and lower layer.
 17. The methodaccording to claim 16, wherein said seaming member includes an insertionelement and a connecting element.
 18. The method according to claim 17,wherein said insertion element is disposed in said pocket.
 19. Themethod according to claim 17, wherein said insertion element is a wovenweb.
 20. The method according to claim 17, wherein said connectingelement is a seaming loop or a spiral.
 21. The method according to claim16, wherein said main portion is formed from a plurality of interwovenlayers.
 22. The method according to claim 16, wherein each of said upperand lower layers is a single layer having a plurality of interwovenmachine direction (MD) yarns and cross-machine direction (CD) yarns. 23.The method according to claim 22, wherein CD yarns are absent from saidupper and lower layers at predetermined locations.
 24. The methodaccording to claim 23, wherein said predetermined locations in saidupper layer align vertically with said predetermined locations in saidlower layer.
 25. The method according to claim 24, wherein a thread issewn through said predetermined locations to attach said seaming memberto said upper and lower layers.
 26. The method according to claim 16,wherein said seaming member is sewn to said upper and lower layers. 27.The method according to claim 16, wherein said seaming member is sewnin-line.
 28. The method according to claim 16, wherein said seamingmember is a single piece having the same width of the fabric.
 29. Themethod according to claim 16, wherein said seaming member is formed fromsmaller segments each having less than the width of the fabric.
 30. Themethod according to claim 16, wherein the industrial fabric is a dryerfabric for use in a drying section of a papermaking machine.